示例:

some_dict = {}
some_dict[5.5] = "Ruby"
some_dict[5.0] = "JavaScript"
some_dict[5] = "Python"

輸出:

>>> some_dict[5.5]
"Ruby"
>>> some_dict[5.0]
"Python"
>>> some_dict[5]
"Python"

"Python" 消除了 "JavaScript" 的存在?

說(shuō)明:

• Python 字典通過(guò)檢查鍵值是否相等和比較哈希值來(lái)確定兩個(gè)鍵是否相同.
• 具有相同值的不可變對(duì)象在Python中始終具有相同的哈希值.

>>> 5 == 5.0
True
>>> hash(5) == hash(5.0)
True

注意: 具有不同值的對(duì)象也可能具有相同的哈希值（哈希沖突）.
當(dāng)執(zhí)行 some_dict[5] = "Python" 語(yǔ)句時(shí), 因?yàn)镻ython將 5 和 5.0 識(shí)別為 some_dict 的同一個(gè)鍵, 
所以已有值 "JavaScript" 就被 "Python" 覆蓋了.